Memory devices for storing and retrieving data are known in the art. For example, radio frequency ("RF") tags are available from a number of manufacturers, including Texas Instruments of Dallas, Tex. and Omron of Japan. The manufacturing of memory tags such as RF tags typically includes laminating a circuit substrate between a face sheet and a release liner.
The circuit substrate generally carries an electronic structure such as an integrated circuit, and electrical connections such as traces and pads. For RF tag memory devices, an antenna is coupled to one or more pads of the circuit substrate. The electronic structure typically includes a memory portion and a logic portion. The logic portion controls the reading, writing, or manipulating of data in the memory portion. The logic portion further couples the memory portion to the antenna to form a transmitter, receiver, or transceiver for reading or writing data to or from the RF tag. Thus, for example, an RF tag may receive and transmit RF signals to write data to the memory and to read data from the memory.
The face sheet provides a protective layer over one surface of the circuit substrate, thereby protecting the antenna and the electronic structure. A pressure sensitive adhesive may cover a second surface of the circuit substrate to readily affix the memory device to an item or container. The release liner provides a selectively removable protective layer over the pressure sensitive adhesive, which a user removes before applying the memory tag to an item or container.
The existing laminate structures and methods of manufacturing memory tags present certain problems. Due to the typically thin profile of most memory tags, the antenna is usually positioned extremely close to the item or container to which the memory device is affixed. This antenna placement unfavorably interferes with good communications with the memory device, especially when the underlying container is made of metal. This antenna placement also reduces the overall range of the memory device.
While it is possible to build a relatively high profile memory device that spaces the antenna further away from the package or item than current memory devices, such a high profile device leads to other problems. For example, memory devices such as RF tags may carry printed indicia on a visible surface of the RF tag. The indicia may be printed on the RF tag by the end-user, after the device has been manufactured. Printing on a relatively high profile device would be extremely difficult and would require specialized equipment, if possible at all. Another problem in current memory device structures is that the integrated circuit and other electronic structures typically produce a non-flat surface and thus a discontinuity in the surface of the face sheet, significantly interfering with printing on the face sheet. Such printing interference necessarily lowers print quality. The discontinuity may also interfere with manufacturing operations after forming or placing the electronic structures on the circuit substrate.